Consensus Method for a Distributed Database

3. The computer-implemented method according to claim 1, wherein verifying the first combined state is performed by all main nodes or by one randomly selected main node.

5. The computer-implemented method according to claim 1, wherein in case of a mismatch between the first combined state and the global state a new first combined state is determined and verified until consensus is reached.

6. The computer-implemented method according to claim 1, wherein in case of a mismatch between the second combined state and the global state a new second combined state is determined and verified until consensus is reached.

7. The computer-implemented method according to claim 1, wherein in case of a mismatch between the first combined state and the global state and/or between the second combined state and the global state different main nodes are selected to determine a new global state.

8. The computer-implemented method according to claim 1, wherein in case of a mismatch between the first combined state and the global state and/or between the second combined state and the global state the subset according to the mismatch is identified and at least one transaction is rolled back for that subset.

9. The computer-implemented method according to claim 1, wherein the distributed database is a blockchain.

10. A computer program product, comprising a computer readable hardware storage device having computer readable program code stored therein, said program code executable by a processor of a computer system to implement a method according to claim 1 when the computer program product is run on a computer.

11. A distributed database comprising main nodes, each main node storing a dataset, and a plurality of subsets of nodes, each subset storing a part of the dataset, configured to perform a consensus method according to claim 1 for obtaining a valid global state of the distributed database.